Many different kinds of sabots are known, such as those described in U.S. Pat. Nos. 3,164,092, 3,738,279, 3,802,345, 4,574,703, 4,653,404, 5,339,743, 6,829,997. Sabots are one solution, but not the only solution, for encasing some or all of a projectile, typically only until launch, typically to facilitate launching of a projectile whose diameter is much less than that of the barrel of the launcher.
Both smoothbore and rifled firearm barrels are known. Rifling refers to a helical pattern of grooves along the inside diameter of a barrel which imparts spin to an exiting projectile about the long axis thereof, thereby gyroscopically stabilizing and when necessary “averaging out” minor structural discrepancies of the projectile that might otherwise shift the trajectory, so as to enhance its accuracy. Rifling is characterized by a “twist rate” typically indicating the distance or number of diameters a projectile travels while completing one full revolution, such as “1 turn in 10 inches” (1:10 inches), “1 turn in 30 cm” (1:30 cm), or 18 (e.g.) barrel diameters per turn. Rifling is typically formed by cutting out “grooves”; the resulting ridges are called lands. The number of grooves (or ridges) may for example be 28 or 30, for a 120 mm barrel.
The disclosures of all publications and patent documents mentioned in the specification, and of the publications and patent documents cited therein directly or indirectly, are hereby incorporated by reference.